Plummet in Insect Population in Puerto Rico Rainforest Linked to Climate Change

A new study shows Puerto Rico’s Luquillo rainforest food web is on the brink of collapse due to temperature rises.
Jessica Miley

Insect numbers in Puerto Rico’s Luquillo rainforest have plummeted 10 to 60 times since the 1970’s a new report has revealed. This alarming fall in numbers has led to the unraveling of the of the forests food web causing spikes in drops in other animals such including a decline in the animals that consume insects such as frogs, lizards, and birds.

The study also indicated that overall temperature in the forest had risen by 2 degrees, suggesting climate change is the reason for the devastation of the forest ecosystem. Luquillo rainforest is the only tropical forest in the U.S. national forest system.

Scientists continue research started in 1970's

Data for the study was taken between 1976 and 2012 at two mid-elevation habitats in the rainforest. The scientists used the same methods as researchers in the 1970’s to trap and weigh insects, they found the overall mass weight of the creatures had dropped 4 to 8 times in clean sweeps, and 30 to 60 times in sticky traps.

While the scientists are keen to show the increased temperature data as a likely indicator they also make it clear that forests are complex systems and prone to large weather patterns such as El Niño/Southern Oscillation. However, they also urge that more research is funded to examine more closely the effects of climate change on large forest ecosystems.

Insects are building a base of complex ecosystem

The findings from Luquillo are likely to be similar to other forest systems around the world. Rainforests typically have very specific temperature ranges and even slight increases can have adverse effects on the complex food web that supports them.

Insects are a crucial part of any ecosystem, not only are they a protein-rich food source for larger animals they also have important roles in processing forest waste and spreading soil and litter. Harvard biologist Edward O Wilson, once observed: “If all humankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed 10,000 years ago. If insects were to vanish, the environment would collapse into chaos.”

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Urban insects numbers rapidly decline

Unfortunately, the decline in insects isn’t contained to the rainforests. In the United Kingdom, insect numbers have been plummeting since the 1970’s. The V-moths (Marcaria wauaria) population has experienced a 99% fall between 1968 and 2007 and is now threatened with extinction.

These urban declines may be due to a combination of pollution, urbanization and temperature rise. It’s clear there is a global insect crisis.

This urgent problem is made even more serious when talk turns to insects as a food source for humans. In many parts of the world, insects have long been a protein-rich, easily accessible food. Spreading the notion of eating insects is one idea to move the world away from agricultural meat sources.

However, these studies show that there might not even be enough insects for that. The study was published on Monday in the Proceedings of the National Academies of Sciences.



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